Slot array antennas have been disclosed in a number of prior patents. U.S. Pat. No. 2,433,924, for example, discloses an antenna adapted to provide non-directional radiation in a horizontal plane.
U.S. Pat. No. 2,570,824 discloses a slot antenna intended to be flat for airborne use and have a band width of several percent through the provision of a plurality of slots fed by a resonant cavity. U.S. Pat. No. 2,589,664 also discloses a wide band airborne antenna having a plurality of slots and designed to be incorporated into an aircraft without protruding surfaces. Thus, a structural member of the aircraft, such a vertical stabilizer, is provided with slots on opposite sides of the stabilizer, covered with dielectric material, and fed from a single T-shaped cavity so that the radiated patterns of each of the slots are in phase in the fore and aft directions of the aircraft and radiate horizontally polarized energy.
U.S. Pat. No. 2,628,311 discloses a broadband, multiple-slot antenna system having a plurality of slots spaced apart by a distance that is small with respect to the wavelength and fed by resonant chambers to provide a substantially uniform current distribution over the outer surface of the antenna structure. The multi-slot antenna can be either a planar or cylindrical array of slots.
U.S. Pat. No. 2,981,949 discloses an antenna intended primarily for airborne application provided with a plurality of center-fed, radially expanding, waveguide portions to project energy radially outwardly from the center so that the energy may leak through annular slots in the walls of each of the radially expanding waveguide sections to provide an omnidirectional or toroidal beam expanding in the horizontal direction. By progressively feeding adjacent sectoral waveguides, a sectoral beam may be created and swept or scanned about in the horizontal plane about the vertical axis of the antenna.
U.S. Pat. No. 4,647,940 discloses a parallel waveguide, microwave antenna that may be inexpensively manufactured and reliably used even though exposed to the elements. The antenna is comprised of a pair of plates of dielectric material, preferably glass, spaced apart and separated by air, inert gas or vacuum, preferably air, with one of the plates having a metallized surface to provide a ground plane and the other plate having a metallized surface defining a series of waveguide slots or apertures arranged and configured to provide a radiated beam having desired polarization beam, with beam characteristics and parameters as desired. The metallized portions of the two plates are arranged to face each other and define the enclosed air space, and the two plates hermetically are sealed at the edges and fed by a central coaxial cable so that energy introduced to the antenna structure from the central waveguide propagates outwardly in the enclosed air dielectric as expanding circles and escapes to free space by radiation at the plurality of slots or aperatures.
U.S. Pat. No. 4,633,262 discloses a TV receive-only antenna of the type disclosed in U.S. Pat. No. 4,647,940 that may be inexpensively manufactured and reliably used outdoors. The TV receive-only antenna is comprised of a first glass plate having a metallized surface and a second glass plate having a metallized circuit pattern designed to receive a planar wave as, for example, from a geostationary equatorial satellite. The glass plates are arranged with their metallized surfaces facing each other and spaced from each other to define an air space between the circuit pattern and ground plane and sealed at the edge to protect the metallized surfaces from the environment.
U.S. Pat. No. 4,825,221 discloses a dielectric transmission line for transmitting electromagnetic waves radiated from one end portion thereof into surrounding space by providing an end portion of the dielectric line contoured to a configuration required for emitting electromagnetic waves in the form of predetermined wave front. In accordance with this patent, the dielectric line may have a plurality of end configurations, including a convex face, a concave face, a conical end and a flat end; and the end portion of the dielectric line may be provided with varying dielectric constants to shape the wave emitted from the end of the dielectric.
Notwithstanding the prior development efforts represented by the patents above, a need still exists for an efficient, broadband antenna with unidirectional sensitivity, especially an antenna having a single-feed means, that may be inexpensively manufactured and adapted to receive communications from satellite transponders.